> There are only 4 successful general purpose production OSes
Feel like you are using a very narrow definition of "success" here. Is BSD not successful? It is deployed on 10s of millions of routers/firewalls/etc in addition to being the ancestor of both modern MacOS and PlaystationOS...
Just because they have been made before LLMs doesn't mean it can be done again, since there was just one success (GNU/Linux) and that success makes it much harder for new OSes since they need to better then it